FY24 Topic Areas Research and Technology Development (TRTD) - A new method for testing star formation and metal transport theories in galaxies

Sep 15, 2026

FY24 TRTD proposes a new observational technique to test competing theories of star formation and the resulting metal transport in galaxies by using the nitrogen abundance distribution. Stellar feedback from young stars regulates star formation by heating, ionizing, and dispersing molecular gas, yet the coupling to the interstellar medium remains poorly quantified. The work targets Galactic star-forming regions using Hydrogen RRL measurements and archival [NII] data in Carina. FY24 efforts delivered H-RRL mapping and physical-property derivations that enable future constraints with [OIII] 88 μm.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages1

Reading Time3 min

AccessFree to download

Strategic Focus Area

Formation and evolution of galaxies

Background

Stellar feedback and energy coupling

Objectives

Quantify feedback energy and momentum in the ISM

Approach and Results

Completed H-RRL mapping in FY24

Nitrogen abundance distribution in Carina

Electron temperature mapping and implications

Line-width fitting with [NII] and RRL

Significance/Benefits to JPL and NASA

Support for PRIMA probe and future missions

National Aeronautics and Space Administration FY24 Topic Areas Research and Technology Development (TRTD) A new method for testing star formation and metal transport theories in galaxies Principal Investigator: Jorge Luis Pineda Galvez (326); Co-Investigators: William Langer (320), Mathew Orr (Rutgers University/Flatiron Institute) Strategic Focus Area: Formation and evolution of galaxies Background: The regulation of star formation in galaxies plays a fundamental role driving galaxy evolution by determining their stellar mass growth and chemical enrichment. Stars form out of the gravitational collapse of dense molecular gas, and, as they form and enter the main sequence, they produce UV and visible photons that can heat and ionize their surroundings, and stellar winds that push accreting material away from the stars. This feedback can reduce the amount of molecular gas available to form additional stars, or, atthe very least, reduce the efficiency at which additional stars might form. At later times (>4 Myr) supernova explosions can inject additional energy and momentum, further slowing star formation and destroying their progenitor clouds. These processes together are known as stellar feedback. A key unknown in our understanding of the role of star formation in galaxy evolution is the coupling of the energy produced by stellar feedback with its surrounding interstellar medium. The distribution of the elemental abundance of nitrogen, which traces metallicity, can be used to determine the efficiency at which energy from stellar feedback is injected into the ISM, and thus we propose that the nitrogen abundance can be used to test competing star-formation theories. Objectives: The objective of this task is to quantify the energy and momentum that stellar feedback has injected into the ISM of Galactic star forming regions to test competing star formation hypotheses. This objective will be accomplished by obtaining Hydrogen RRL (HRRL) measurements, which provide the ionizing and kinetic energy of the gas, in a statistically significant sample of Galactic star forming regions covering a range of masses, luminosities, and evolutionary stages. In the program proposed here we will combine the H RRL measurements with archival [NII] observations in the Carina region to provide the first quantitative assessment of the two competing star formation hypotheses using the nitrogen abundance distribution. Approach and Results: During FY24 we completed the H-RRL mapping as shown in Figure 1. We combined archival ISO and SPIFI data to determine the volume and column densities of low and high ionized gas in the Carina Nebula. We find an extended highly ionized component with N ++ and O++ present with electron densities of about 300 cm-3 . A low ionization component with only N +^ is also present with electron densities of 30-150 cm-3 . H+ and N+ column densities peak at the location of the stellar cluster in Carina II (Figure 2) . We also studied the contribution from doubly ionized nitrogen in this region finding that it is the highest near the stellar clusters in Carina (Figure 3) . The ratio of the total nitrogen (N+ +N++) to ionized hydrogen, the nitrogen abundance, shows a relatively flat distribution with respect to the location of stellar clusters (Figure 4) . This flat distribution tentatively suggests that stellar feedback is strong enough to distribute newly formed metals in the ISM at relatively short timescales. Future observations of the [OIII] 88μm line are important for characterizing this highly ionized component. We also derived an electron temperature map in the Carina Nebula using the ratio of the RRL to radio continuum emission. The electron temperature is a key ingredient in the derivation of the Nitrogen abundance distribution. In Figure 5 we show the distribution of electron temperatures derived across the Carina nebula. We find a temperature range between 3000K and 12000K with a tendency for electron te

FAQs

What is the main goal of this FY24 TRTD task?

Quantify the energy and momentum injected by stellar feedback into the ISM of Galactic star-forming regions to test competing star-formation hypotheses.

How does nitrogen abundance help test star-formation theories?

The nitrogen abundance, traced by elemental distribution of nitrogen, indicates the efficiency of energy injection from stellar feedback into the ISM, enabling comparison of competing theories.

What key observational results were completed during FY24?

FY24 completed H-RRL mapping for the Carina region, combined archival ISO and SPIFI data to estimate ionized-gas volume and column densities, and derived nitrogen abundance and electron temperature distributions.

Sep 15, 2026

Uploaded by Olivia Brown